Answer:
y=2x+3
Step-by-step explanation:
the normal charge is 3 + 2 x number of days so this equation is the correct one.
<u>Answer:</u>
or 
<u>Step-by-step explanation:</u>
We are given the following function of x and we are to find the value of
:

Substituting the given value (7) in the above function to get:





or 
You were right 24 is the answer. :)